ripe Pu-erh tea

The term 「回甘」 (in translation: "huigan") is often treated as a central concept when discussing ripe-style pu-erh tea made by moistening and piling leaves for microbially involved post-fermentation. An article by a writer in the Chinese tea trade, titled 「普洱茶品茶术语解读」 (in translation: "Interpreting Pu-erh Tea-Tasting Terminology"), discusses huigan, shengjin (a sensation of salivation), houyun, and suohou (throat tightness), mainly with pu-erh tea in view. A separate article of the same kind, titled 「关于普洱茶的回甘、生津、回甜」 (in translation: "On huigan, shengjin, and huitian in pu-erh tea"), also treats the term, suggesting it is recurring vocabulary for this tea.

These are explanatory articles written by tea-trade practitioners, not peer-reviewed studies; they give no supporting sensory-panel measurements or chemical analysis. The cited articles do not quantify pu-erh tea’s bitterness or how fermentation might change it into huigan.

In quantitative descriptive analysis (QDA) comparing one commercial aged pu-erh tea product after 1, 3, 5, 7, and 9 years of storage, bitterness scores fell significantly from 2.5 to 1.17 and astringency scores from 3.17 to 1.67 as storage lengthened (p<0.05). At the same time sweetness scores increased significantly from 6.17 to 7.67. These figures describe declining bitterness and astringency and rising sweetness over storage, but they come from one product and one lot and cannot be generalized automatically to other brands.

In HPLC analysis of the same product, epigallocatechin gallate (EGCG), a major contributor to bitterness and astringency, peaked at 0.82±0.02 mg/g in storage year 3 and then decreased significantly to 0.27±0.03 mg/g by year 9. Declines in monomeric catechins, including EGCG and epicatechin gallate (ECG), correlated positively with lower sensory bitterness and astringency scores (p<0.05 or p<0.01). EGCG is not the only contributor to bitterness; other nonvolatile constituents, including theabrownins, also contribute to taste.